* Quantity : 20
* O.D. : 3 mm / 0.118 in
* Wire Diameter : 0.45 mm / 0.017 in
* Free Length : 13 mm / 0.511 in
* Material : SUS304-WPB Distinguishing Features:
Both ends are closed but are NOT ground square.
for spring load
Spring force is dependent on the distance it is displaced (compressed or extended).
Calculating the load
Compression springs - To find the load at any working length, when free length
and rate are given, use the formula:
P = R x F
where P is the load in lbs; R is the rate in lbs per inch;
F is the deflection from free length.
Example: Given a free length of .750" and a rate of 22 pounds per inch,
find the load at .500" working length.
P = 22 x (.750-.500) = 22 x .250 = 5.5lbs
Extension springs - To find the load at any working length,
when the free length, rate and initial tension are given, use the formula:
P = (R x F) + I.T.
where P is the load in lbs; R is the rate in lbs per inch;
F is the deflection from free length; I.T. is the initial tension.
Example: Given a free length of 1", a rate of 6.9 pounds per inch,
and .7 pounds initial tension, find the load at 1.500".
P = [6.9 x (1.500-1.000)] + .7 = (6.9 x .500) + .7 = 3.45 + .7 = 4.15 lbs
Determining rate
How to determine rate - Rate, which is the change in load per unit deflection,
may be tested by the following procedure:
1. Deflect spring to approximately 20 percent of total available deflection (free length, minus solid height)
and measure load (P1) and spring length (L1).
2. Deflect spring not more than 80 percent of total available deflection and measure load (P2)
and spring length (L2). Be certain that no coils (other than closed ends) are touching at L2.
3. Calculate rate (R) lb. per in.
R = (P2 - P1) / (L1 - L2)